The 1st step: Use software to find and remove infections
Your internet security program will most likely do its best to ensure that viruses are never installed. But if you suspect a virus has infected your system, run your internet security program – it will quarantine and delete virus infected files on your computer.

The 3rd: DIY style
Alternatively, if you want to have a stab at removing the virus or Trojan yourself, visit the BullGuard Antivirus Forum where you can find step-by-step guides on how to remove viruses manually.
Please be warned that you will be stepping into Techie Territory at your own peril. If you don’t feel particularly html-savvy this might not be the place for you...